U.S. patent application number 14/530723 was filed with the patent office on 2015-03-26 for wave energy converter with concurrent multi-directional energy absorption.
The applicant listed for this patent is John W. Rohrer. Invention is credited to John W. Rohrer.
Application Number | 20150082785 14/530723 |
Document ID | / |
Family ID | 52689734 |
Filed Date | 2015-03-26 |
United States Patent
Application |
20150082785 |
Kind Code |
A1 |
Rohrer; John W. |
March 26, 2015 |
Wave Energy Converter With Concurrent Multi-Directional Energy
Absorption
Abstract
An ocean wave energy converter (WEC) using one or more elongated
light-weight low-cost surface floats, oriented and self-orienting
parallel to oncoming wave fronts are mechanically linked to a
motion stabilized or fixed frame or base through one or more power
take-offs in such manner that multi-directional rotational and
translational wave-induced forces and relative motion between the
float(s) and base are efficiently captured. Some embodiments have
at least one forward positioned float that moves upward and
rearward on wave crests and downward and forward on ensuing wave
troughs to capture a majority of both heave and surge wave energy
components. Other embodiments also provide apparatus and means to
totally submerge the floats during severe seas or adjust submerged
depth and float mass to optimize performance.
Inventors: |
Rohrer; John W.; (York,
ME) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Rohrer; John W. |
York |
ME |
US |
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|
Family ID: |
52689734 |
Appl. No.: |
14/530723 |
Filed: |
November 1, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14101325 |
Dec 9, 2013 |
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14530723 |
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13506680 |
May 8, 2012 |
8614520 |
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14101325 |
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61996338 |
May 5, 2014 |
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Current U.S.
Class: |
60/500 |
Current CPC
Class: |
Y02E 10/30 20130101;
F05B 2270/18 20130101; Y02E 60/16 20130101; Y02E 10/38 20130101;
F03B 13/182 20130101; F03B 13/186 20130101; Y02E 60/17
20130101 |
Class at
Publication: |
60/500 |
International
Class: |
F03B 13/16 20060101
F03B013/16; F03B 13/10 20060101 F03B013/10 |
Claims
1. A wave energy converting device comprising: at least one
elongated surface float or buoyant flap having a center of buoyancy
and having a wave impacting forward face wherein the face is
oriented or self-orienting substantially parallel to prevailing or
oncoming wave fronts and wherein the horizontal width of the face,
alone or in combination with adjacent float faces, is greater than
the float fore-to-aft depth measured excluding any float
attachments, extensions or appendages; a frame or base stabilized
against wave-induced heave, surge, and pitch motion, or a
stationary or fixed base having a portion to which the at least one
float is movably connected by at least one rotating swing arm,
linear translating arm, or rotating and translating compound-motion
connecting arm, wherein the at least one arm is rotatably connected
to the frame or base at an arm-to-frame hinge point substantially
below the still water line (SWL), and rearward or forward of the at
least one float's center of buoyancy in still water, whereby the at
least one arm controls the orientation and path of wave-induced
relative motion between the at least one float and the frame or
base in such a manner that the float rotates, translates, or both
rotates and translates concurrently both vertically and
horizontally relative to the arm's connection point to the frame in
response to wave induced-forces on the float; frame or base
position stabilizing, fixing or anchoring devices, directly or
indirectly connected to the frame or base, selected from the group
consisting of the seabed, shorelines, breakwaters, seawalls,
platforms, pilings, gravity weights, water or solid ballasts,
anchors, mooring lines, seabed affixed or floating off-shore
towers, floats or vessels, affixed surface buoys, drag plates or
planes, and combinations thereof; and, at least one power take off
(PTO) apparatus secured to or within the frame or float and
configured to be driven by the at least one force generated by the
wave-induced relative motion between the at least one float and the
frame through the at least one arm.
2-27. (canceled)
28. The device of claim 1 wherein the elevation or submerged depth
in still water and mass of the at least one float or flap can be
controllably lowered or raised by increasing or decreasing the
float's seawater ballast or buoyancy by raising or lowering the
frame or frame attachment points by increasing or decreasing frame
seawater ballast or using the at least one PTO apparatus or an
auxiliary drive to force submergence of the at least one float,
frame, or the at least one frame-to-float attachment point.
29. The device of claim 1 wherein the at least one buoyant float or
flap has at least one cavity and at least one aperture to
controllably admit or release seawater to increase or decrease the
mass or buoyancy of the at least one float or flap.
30. The device of claim 1 wherein the at least one arm is a
parallel pair of swing arms, each rigidly or pivotably attached at
separate locations to the at least one float or flap and each
pivotably attached at separate locations to the frame or base to
form arm-frame hinge points, wherein the movement of the at least
one float and the corresponding parallel pair of swing arms drive
the at least one PTO.
31. The device of claim 1 wherein the at least one arm is two arms
or arm pairs, the first arm being attached to and below the at
least one float or flap and oriented substantially vertically
allowing substantially vertical float motion through its connection
with a second arm, or carriage translating on the second arm, the
second arm being movably or rigidly attached to the frame or base
substantially horizontally to permit substantially horizontal or
lateral float motion, both arms driving a common PTO, or each
driving separate PTOs.
32. The device of claim 1 wherein the at least one arm is two arms
or arm pairs, the first arm being attached to and below the at
least one float or flap and pivotably secured at its lower end to a
carriage moving substantially laterally on a substantially
horizontally or laterally oriented second arm, the rotation of the
first pivoting arm and the translation of the second lateral arm or
arm pairs, or the carriage, each driving at least one PTO.
33. The device of claim 1 wherein the angle between the at least
one float arm-to-frame hinge point and the float's center of
buoyancy at the still water line can be established and controlled
by lowering or raising the frame, the arm-to-frame hinge point, by
extending one or more counter weights from the arm forward or aft
of the hinge point, or by adjustably changing the length of the
arm.
34. The device of claim 1 further comprising at least one second
aft float oriented substantially parallel to, and located
substantially aft of, the at least one float and the at least one
arm-to-frame hinge point, wherein the second float is secured by
aft float arms or appendages of the at least one second float
rotatably or rigidly connected to the frame or base either
substantially below, in close proximity to, or substantially above
the SWL with the second float driving a second PTO when the second
float's arms are rotatably connected to the frame, and wherein the
second float's arms can be released to a substantially vertical
orientation to provide residual buoyancy when the frame and the at
least one float are submerged, and wherein the at least one second
float provides additional pitch stability to the frame.
35. The device of claim 30 further comprising at least one
horizontal torque conveying tube, rod, or shaft located at one or
more of the at least one frame or float's swing arm pivot points,
rigidly connected to, and rotating with, two or more parallel swing
arms maintaining the parallel orientation of the swing arms when
waves apply unequal forces to the at least one elongated float.
36. The device of claim 1 wherein the length of the at least one
float arm is measured along the axis line from the arm's hinge
point with the frame or base through the float's center of
buoyancy, which exceeds 1/2 of the float's vertical height
excluding any attachments, extensions, or appendages.
37. The device of claim 1 wherein the at least one float is
comprised of an elongated buoyant rotor comprised of at least two
blades or foils rotating about a common horizontal axis driving a
first PTO, the rotor being pivotably, or pivotably and
translationally, connected to the frame by the at least one arm,
wherein the arm drives at least one additional PTO.
38. The device of claim 1 further comprising: a frame or base that
in combination with the at least one float is buoyant and is
pivotably attached up sea of the at least one float's forward face
to a single pivoting point on a mooring, piling, or stabilizing or
anchoring device to permit at least horizontal plane pivoting and
to further permit the float's forward face to be self-orienting
parallel to oncoming wave fronts that apply lateral impact force to
the float's forward face; and, a downward sloping wave focusing or
shoaling plane, wherein the shoaling plane at least partially
precedes the at least one float to direct wave energy from water
depths below the float's forward face toward the at least one float
and float face.
39. A wave energy converting device comprising: at least one
elongated surface float or buoyant flap having a center of buoyancy
and having a wave impacting forward face, wherein the face is
oriented or self-orienting substantially parallel to prevailing or
oncoming wave fronts, and wherein the horizontal width of the face,
alone, or in combination with adjacent float faces, is greater than
the float fore-to-aft depth measured excluding any float
attachments, extensions or appendages; a frame or base stabilized
against wave-induced heave, surge, and pitch motion, or a
stationary or fixed base having a portion to which the at least one
float is rotatably connected to the frame or base with at least two
swing arms, one located above the other, at two frame or base
arm-to-frame hinge points located substantially below, in close
proximity to, or substantially above the still water line, wherein
one swing arm-to-frame hinge point is above, fore, or aft of the
other, and wherein the two arms are also rotatably connected to the
at least one float at two float hinge points, one above, fore, or
aft of the other, wherein the dual pivoting arms control the
angular orientation of the at least one float, the orientation of
the at least one float's wave impacting forward face, and the
concurrent wave-induced horizontal and vertical motion of the at
least one float relative to the frame or base; frame or base
position stabilizing, fixing or anchoring devices, directly or
indirectly connected to the frame or base, selected from the group
consisting of the seabed, shorelines, breakwaters, seawalls,
platforms, pilings, gravity weights, water or solid ballasts,
anchors, mooring lines, seabed affixed or floating off-shore
towers, floats or vessels, affixed surface buoys, drag plates or
planes, and combinations thereof; and, at least one PTO apparatus
secured to or within the frame or float and configured to be driven
by force generated by the wave-induced relative motion between the
at least one float and frame through at least one of the dual swing
arms.
40. The device of claim 39 wherein the at least one float has a
center of buoyancy, wherein in still water, the center of buoyancy
is substantially above or forward of the frame pivot point of at
least one of the dual swing arms with at least one of the two
arm-to-frame pivot points located substantially below the still
water line.
41. The device of claim 39 wherein the center of buoyancy of the at
least one float, in still water, is aft of the arm-to-frame pivot
point of at least one of the dual swing arms with at least one of
the two arm-to-frame pivot points being located substantially above
the still water line.
42. The device of claim 39 wherein the elevation or submerged depth
in still water and mass of the at least one float or flap can be
controllably lowered or raised by increasing or decreasing the
float's seawater ballast or buoyancy by raising or lowering the
frame or frame attachment points by increasing or decreasing frame
seawater ballast or using the at least one PTO apparatus or an
auxiliary drive to force submergence of the at least one float,
frame, or the at least one frame-to-float attachment point.
43. The device of claim 39 wherein the at least one float or
buoyant flap has at least one cavity and at least one aperture to
controllably admit or release seawater to increase or decrease mass
and decrease or increase its buoyancy.
44. The device of claim 39 wherein the frame or base in combination
with the at least one float is buoyant and is pivotably attached up
sea of the at least one float's forward face to a single pivoting
point on a mooring, pile, tower, or stabilizing or anchoring device
to permit at least horizontal plane pivoting resulting in the
float's forward face being self-orienting parallel to oncoming wave
fronts that apply lateral impact force to the floats forward
face.
45. The device of claim 39 further comprising a downward sloping
wave focusing shoaling plane, wherein the shoaling plane at least
partially precedes the at least one float to direct wave energy
from water depths below the float's forward face toward the
face.
46. The device of claim 39 further comprising at least one second
float oriented substantially parallel to, and located substantially
aft of, the at least one float and further located aft of the
arm-to-frame hinge points of the at least one float with second
float arms or appendages secured to the at least one second float
and rotatably connected to one or more hinge points on the frame or
base either substantially below, in close proximity to, or
substantially above the still water line, wherein the at least one
second float drives a second power take-off, and wherein the second
float-to-frame dual swing arm angles, at still water, can be
adjusted and optimized by lowering or raising the frame or float to
frame hinge points by either mechanical means or frame or float
buoyancy adjustment, or by using one or more counterweights located
forward or aft of the frame hinge points.
47. A wave energy converting device comprising: at least one
elongated surface float or buoyant flap having a center of buoyancy
and having a wave impacting forward face wherein the face is
oriented or self-orienting substantially parallel to prevailing or
oncoming wave fronts and wherein the horizontal width of the face,
alone, or in combination with adjacent float faces, is greater than
the float fore-to-aft depth measured excluding any float
attachments, extensions or appendages; a frame or base stabilized
against wave-induced heave, surge, and pitch motion or a fixed
stationary base having at least one pivoting arm-to-frame
connection point to which the at least one float is connected by at
least one arm, wherein such connection allows both rotation about,
and translation through, the arm-to-frame connection point; at
least one arm or arm pair rigidly or pivotably connected to the at
least one float and pivotably connected to the frame or base
substantially below, in close proximity to, or substantially above
the still water line, allowing concurrent rotation and linear
translation of the arm about and through the frame connection pivot
point, whereby concurrent translation of the arm and the arm's
rotation about its arm-to-frame pivot point controls the float
orientation and path of wave-induced relative motion between the at
least one float and the frame or base; frame or base position
stabilizing, fixing or anchoring devices, directly or indirectly
connected to the frame or base, selected from the group consisting
of the seabed, shorelines, breakwaters, seawalls, platforms,
pilings, gravity weights, water or solid ballasts, anchors, mooring
lines, seabed affixed or floating off-shore towers, floats or
vessels, affixed surface buoys, drag plates or planes, and
combinations thereof; and, one or more PTO apparatus secured to or
within the frame or float and configured to be driven by the
concurrent rotational and translational forces generated by the
wave-induced relative motion of the at least one float and the
frame through the at least one arm.
48. The device of claim 47 wherein the at least one float or
buoyant flap has at least one cavity and at least one aperture to
controllably admit or expel seawater to increase or decrease its
mass and decrease or increase its buoyancy.
49. The device of claim 47 wherein the elevation or submerged depth
and mass of the at least one float or flap can be controllably
lowered or raised in still water by increasing or decreasing the
float's seawater ballast or buoyancy by raising or lowering the
frame or frame attachment points by increasing or decreasing frame
seawater ballast or using the at least one PTO apparatus or an
auxiliary drive to force submergence of the at least one float,
frame, or the at least one frame-to-float attachment point.
50. The device of claim 47 wherein the frame or base in combination
with the at least one float is buoyant and is pivotably attached up
sea of the at least one float at a single pivoting point to a
mooring, pile, tower, or stabilizing or anchoring device that
permits at least horizontal plane pivoting resulting in the float's
face being self-orienting parallel to oncoming wave fronts that
apply lateral impact force to the float's forward face.
51. The device of claim 47 further comprising a downward sloping
wave focusing shoaling plane, wherein the shoaling plane at least
partially precedes the at least one float to direct wave energy
toward the float's forward face from water depths below the float's
forward face.
52. The device of claim 47 further comprising at least one second
float oriented approximately parallel to, and located substantially
aft of, the at least one float and the at least one float's
arm-to-frame hinge points, wherein the second float secured by at
least one aft float arm or appendages of the at least one second
float rotatably or rigidly connected to the frame or base either
substantially below, in close proximity to, or substantially above
the SWL, wherein the second float arms drive a second PTO when the
second float is rotatably connected to the frame and wherein the
second float's arms can be released in a substantially vertical
orientation to provide residual buoyancy when the frame and the at
least one float are submerged, and wherein the second float
provides additional frame pitch stability.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a Continuation-In-Part of U.S. Regular Utility
application Ser. No. 14/101,325 filed Dec. 9, 2013, which is a
Continuation-In-Part of U.S. Regular Utility application Ser. No.
13/506,680 filed May 8, 2012, now U.S. Pat. No. 8,614,520 and
claims the benefit of U.S. Provisional Application Ser. No.
61/996,338 filed May 5, 2014, the contents all of which are
incorporated in their entirety herein by reference.
FIELD OF THE DISCLOSURE
[0002] This disclosure relates to the production of electrical
power, pressurized water, or other useful work from surface waves
on a water body. More particularly, this disclosure relates to Wave
Energy Converters ("WEC") of the wave terminator or barrier type,
wherein one or more elongated buoyant surface floats or bodies, or
groups of adjacent floats or bodies are oriented, or
self-orienting, parallel to the prevailing direction of oncoming
wave fronts or swells.
[0003] The disclosure relates primarily to WECs having one or more
floats or bodies linked or connected by one or more swing arms or
other mechanical linkages to one or more stationary or stabilized
bodies, frames, or seabed or shore attachment points. Such linkages
drive a power take off (PTO) and are arranged in such a manner that
the buoyant floats or bodies can rotate and/or translate about the
attachment points, or concurrently move in more than one axis or
direction of motion to thereby allow the WEC to absorb and capture
additional heave (vertical), surge (lateral) and or pitch
(rotational) wave energy from such multi-axis or multi-direction
motion.
[0004] To avoid potentially damaging broadside impacts from extreme
waves during severe sea conditions, or to optimize performance, the
elongated and wave front parallel floats or bodies of several
embodiments of the disclosure can be partially or fully submerged
during severe sea conditions. Such float submergence, and
re-emergence, can be facilitated by any of several means including
forcing float submergence by utilizing the WEC's PTOs (in reverse),
by use of auxiliary drives to force float submergence, or by
altering the submerged depth of the stabilized bodies or frames or
their attachment points to force submergence of the floats under
the still water line, or under oncoming wave troughs, until severe
seas subside.
BACKGROUND OF THE DISCLOSURE
[0005] Ocean wave energy in most northern and southern global
latitudes is several times more concentrated than solar energy, or
the surface winds that produce ocean waves. Ocean waves are also
more consistent and predictable than wind energy and should,
therefore, ultimately result in a lower cost of renewable power.
Yet ocean wave energy technical development and commercial
deployment lags substantially behind wind (including offshore wind)
and solar energy. This is in large part due to the proliferation of
possible and proposed methods of converting wave energy into power
that has diffused public and private efforts so as to limit
resources available to the few WEC concepts that may prove to be
both affordable, effective and survivable.
[0006] Many WEC concepts utilize circular-section buoy-type surface
floats reacting against either a central motion-stabilized vertical
spar (called "heave-only buoys" or "spar buoys" including the
PowerBuoy and WaveBob WECs), or a seabed affixed tensioned cable.
These circular-section buoy-type WECs were initially popular
because circular navigation buoys have proven to survive in extreme
seas and because early university wave tank experiments using
buoy-type "point absorber" WECs showed high capture efficiencies
when conditions of "resonance" (matching WEC moving mass to a
specific wave amplitude and period) were achieved using
wave-tank-generated artificially uniform amplitude and period
waves. Point absorber type WEC performance in real random ocean
wave environments where "resonance" conditions cannot be
established or maintained has been extremely disappointing with
wave energy capture efficiencies typically less than 1/3 of that
achieved in wave tanks. Because these circular floats
move/translate primarily vertically, they are often referred to as
"heave only buoys" and capture little or none of the surge
(lateral) wave-only component.
[0007] During the late 1980's, Salter and others at the University
of Edinburgh proposed a spar buoy having a sloped or inclined spar
called the "Sloped IPS Buoy". This design permitted the buoy or
float to move along the spar in both an upward and a rearward
motion relative to incoming wave crests and return forward and
downward on ensuing wave troughs. Wave tank tests published in 1999
by University of Edinburgh doctoral candidate Chia-Po Lin
established that this sloped-motion-constrained buoy or float
captured both substantial heave and surge wave energy components
even in random wave conditions when the spar was maintained in a
fixed sloped position via attachment to the tank bottom.
[0008] Other early WEC concepts utilize two or more hinged
articulating rafts pointed into (transverse to) oncoming wave
fronts including the Pelamis, Cockerell Raft, McCabe Wave Pump, and
more recently the Crestwing and Columbia Stingray. These
"articulating" type WECs have two or more surface floats or rafts
hinged at or near the sea surface (Still Water Line or "SWL")
preventing significant lateral float translation or movement and
hence limited surge (lateral) wave energy capture. The portion of
adjacent rafts or floats near the common hinge joint also limits
vertical movement of these portions, which reduces "heave" wave
energy capture.
[0009] The "elongated swing arms" or "dual swing arms" or "compound
motion arms" that float relative to fixed or stabilized frame
linkages of the disclosure substantially improve the performance of
all "articulating raft" type WECs. The disclosure improves both
heave wave energy capture (by allowing more vertical
movement/translation near the float/raft surface hinge) more surge
(lateral) wave energy capture by increasing lateral float, raft
movement, or translation.
[0010] Other early concepts, called oscillating water columns or
OWCs, use shore attached, or off-shore floating artificial sea
caves with air turbine equipped blow holes (OceanLinx).
"Articulating raft" and OWC type WECs require large horizontal
plane surface areas per unit of intercepted wave front width that
increases WEC vessel volume, mass and hence capital costs. Another
downside to these designs is that they primarily capture only
"heave" or vertical component wave energy (only 50% of total wave
energy in deep water). Point-absorber, buoy-type, and other
"surface-area-dependent" WECs also have extremely poor (actually
negative) economies of scale. When their capture widths are doubled
to intercept twice the energy containing wave front, their volumes,
weights, and hence costs are tripled increasing rather than
decreasing their capital cost per kilowatt captured.
[0011] While several early WEC concepts (including the early Salter
Duck of the University of Edinburgh) did propose the use of
elongated floats, or groups of adjacent floats, oriented parallel
to (facing) wave fronts to intercept and capture more wave energy
per unit float width, volume, and cost, few wave front parallel
"wave barrier" or "wave terminator" type WECs are currently being
pursued. This is primarily due to their severe sea survival
vulnerabilities. One notable exception are "surge flap" type WECs
that use a buoyant, vertically oriented (in still water) elongated
flap or panel, hinged at its base that rotates about the hinge in
response to lateral (surge) wave forces. This design is currently
being developed by Aquamarine, Resolute, Langlee and others. Most
"surge flap" WECs are of fixed orientation (toward the prevailing
wave front direction), hinged at or near the seabed, in near-shore
locations having less than 20 meters water depth (except for the
Langlee design that uses two parallel buoyant flaps hinged to a
semi-submerged frame).
[0012] The "single elongated arm", "dual swing arm" or
"compound-motion swing arm" float-to-frame linkages of the
disclosure substantially improve the performance of all "surge
flap" type WECs in two ways. The first is to improve the flap's
surge wave energy capture effectiveness by allowing the lower
portion of the flap (near the fixed bottom hinge) to move
laterally. The second improvement is to enable the buoyant flaps to
also capture substantial heave (vertical component) wave energy by
allowing increased concurrent horizontal and vertical flap movement
or translation.
[0013] It is most desirable to have WECs with floating bodies
operate on the ocean surface in deep water (offshore) where the
wave energy resource is greatest and siting conflicts are
minimized. WECs with elongated surface floats oriented parallel to
wave fronts can intercept and potentially absorb several times more
wave energy per cubic meter of float volume, weight, and cost. Few
WECs of this type have been proposed or pursued to date, however,
because WECs with elongated surface floats oriented parallel to
wave fronts must survive broadside impacts against these surface
floats from storm waves that can reach 15 meters height. Several
proposed WECs operate fully submerged using only wave induced
hydrostatic pressure fluctuations. They are deployed either on the
seabed (M3), or substantially below the surface (CETO and AWS II),
but wave energy, predominantly a surface phenomenon, decreases
exponentially with depth. Thus, subsurface deployed WECs can only
access the heave wave energy component (only 50% of total wave
energy at the surface), which results in low wave energy capture
efficiencies.
[0014] Many embodiments of the disclosure overcome the survival
limitations of prior elongated float, surface deployed WECs by
using various methods to totally submerge the floats during severe
sea conditions including those described and claimed in my U.S.
Pat. No. 8,614,520 and in my prior regular utility application Ser.
No. 14/101,325, of which this application is a
Continuation-In-Part. The present disclosure also describes and
claims several ways to link the wave front parallel oriented
elongated floats to stabilizing frames or structures and WEC
Power-Take-Off (PTO) systems in ways that increase the wave induced
horizontal, vertical and/or rotational translation of such surface
floats and, therefore, their wave energy capture efficiency.
SUMMARY OF THE DISCLOSURE
[0015] The WEC embodiments of the disclosure utilize one or more
elongated, relatively light-weight and, therefore, highly
responsive and low cost, self-orienting wave-front parallel surface
floats or multiple adjacent floats. Elongated floats minimize float
volume and hence WEC cost per meter of intercepted wave front. The
axis of movement of the single elongated, or multiple adjacent
floats is dictated by the rotating "swing arm" and/or translating
attachment linkages between the float(s) and the stabilized or
stationary frame, or other stabilizing attachment point(s).
[0016] The attachment linkages or mechanisms disclosed in U.S. Pat.
No. 8,614,520, incorporated herein by reference, describe a single
direction of movement or axis of rotation of the one or more floats
(down sloped linear movement for the embodiment with tracks or down
sloped arcuate rotation for the embodiment with swing arms). This
down sloped movement allows these WECs to capture a majority (but
not all) of both heave (vertical component) and surge (horizontal
component) wave energy. The theoretical maximum amount of wave
energy capture for the heave and surge wave energy components at
any instant for either linear or arcuate down sloped motion of the
float is equal to the sine (for vertical heave) plus cosine (for
lateral surge) of the slope angle (from horizontal), respectively.
For a constant downward sloping slope angle of 45 degrees, for
example, in deep water, where heave and surge wave energy are each
exactly 50% of total wave energy, the theoretical capture limits
are maximized with 0.707 of total heave energy plus 0.707 of total
surge energy and, therefore, a maximum of 70.7% of total wave
energy. For a slope angle of 30 degrees the theoretical maximum
capture efficiency is 68.3% or (0.866+0.50)/2=0.683. Capture
efficiencies above these theoretical maximums are possible in wide
wave tanks using uniform waves and conditions of "resonance"
producing a wave focusing "antenna effect" but this is not
achievable in real open ocean random waves.
[0017] It is most advantageous to allow the direction of movement
and/or axis of rotation of the one or more elongated wave front
parallel surface float(s) of the present disclosure to
theoretically capture 100% of the available heave energy and 100%
of available surge energy (without the benefit of artrficially
induced wave tank conditions of resonance). This is done in the
present disclosure by selecting mechanical linkages between the
elongated float(s), (or multiple adjacent floats forming an
elongated float group) and the frame or other fixed or
motion-stabilized reaction body (through the Power-Take-Off or PTO)
to concurrently and independently allow the floats to move both
vertically (for full or increased heave capture) and horizontally
(for full or increased surge capture) relative to the frame, tower,
or other stabilized reaction body. Heave and surge wave energy for
each float, in most embodiments, are each captured with their own
independent PTOs or generators. In some embodiments, however, they
can be combined to use a single PTO or generator.
[0018] FIG. 15 (which is FIG. 10 in prior application Ser. No.
14/101,325) and FIG. 16 of this disclosure show embodiments of the
present disclosure where concurrent and independent vertical and
lateral translation (FIG. 15) or lateral and rotational translation
(FIG. 16) of the float(s) is obtained. It is generally less
expensive and more reliable, however, in ocean environments to
mount WEC surface floats on swing arms rather than linear tracks.
The slope angle and, therefore, theoretical maximum capture
efficiency for a float vessel supported by swing arms pivoting
around a submerged pivot point (rather than a float on constant
slope angle tracks) is constantly changing, but does not deviate
much between +/-20 degrees from the ideal 45 degrees (if long swing
arms are used), and will still average around 70% capture
efficiency over this swing arc.
[0019] The one or more elongated buoys of the present disclosure
can be hollow or foam filled and fabricated with fiber reinforced
plastics (FRP) or composites, metals (aluminum or steel), or
similar materials. Where hollow floats or floats with internal
cavities are used, it is useful to have either open upper cavities
(like a boat hull) or apertures allowing seawater ballast to
controllably enter or exit the cavities providing supplemental
float mass to enhance wave energy capture efficiency during certain
sea conditions. These structures are also advantageous to reduce
the float's buoyancy, which must be overcome by the WEC's PTOs,
alternative float submerging drives, or the attached submergible
frame, to fully submerge the elongated floats during severe sea
states.
[0020] In some embodiments of the present disclosure, the one or
more floats are elongated with a horizontal plane (defined as the
width of a single float, or the combined width of two or more
adjacent floats) oriented parallel to oncoming wave fronts,
substantially exceeding their fore to aft horizontal depth
(excluding any fore or aft appendages). In some embodiments the
float have a substantially upward or vertically oriented flat or
curvilinear wave impacting forward face, substantially
self-orienting or oriented parallel to prevailing or oncoming wave
fronts. A portion of the wave impacting forward face is generally
below the water surface (in still water) and optionally has a lower
lip or extension plate protruding generally forward of, and/or
downward from, the forward face of the float(s).
[0021] The one or more floats of the present disclosure are
mechanically linked to a motion-stabilized or fixed-position frame,
driving one or more PTO's (or generators), or directly or
indirectly attached to the seabed, shoreline, or an
offshore-submerged or above-surface tower, piling, or surface
vessel. The PTOs can be located at either the float end or
stabilized frame end of the mechanical linkages. In some
embodiments, the PTO is comprised of a direct or indirect
(including gearbox, rack and pinion, linear helix or ball screw,
chain, gear belt and capstan cable) driven rotary electric
generator (advantageously having high torque at low RPM), or a
linear electric generator. Alternatively the PTO(s) can be
comprised of high or low pressure hydraulic motor or turbine-driven
generators with or without fluid accumulators to smooth wave to
wave output surges. The PTOs should include the ability to control
the multi-directional or multi-axis resistive forces applied by the
float(s) against oncoming waves throughout each power stroke (in
one or both directions) during each wave cycle including slowing or
delaying the initial float motion during each power stroke until an
optimal resistive force for that individual or average wave type
has been reached (commonly referred to as "latching"). This can be
accomplished by sensing the amplitude and velocity of each oncoming
wave in advance of its reaching the floats and optimizing, via a
programmable controller, the generator torque or resistive force to
be applied by the float(s) to that wave (or average of several
waves). A "latching brake" can assist the generator with
supplemental resistive torque or force, if needed.
[0022] The mechanical linkage of the present disclosure between the
one or more floats and the motion stabilizing frame or attachment
points is comprised of one or more combinations of rotating swing
arms, fixed or variable length drive bars or arms, linear or
curvilinear tracks or gear racks, or drive cables, chains, belts or
gears. The linkages between the floats and the PTOs are chosen and
arranged such that the float(s) movement concurrently or
independently in vertical, horizontal, and/or rotational
directions, in response to wave-induced forces upon them, is
substantially increased and/or the float's rotational orientation
and wave impacting face angle is optimally maintained or controlled
independent of the float's arc or direction of motion.
[0023] The stabilized frame or other motion stabilized attachment
points to which the swing arms of the present disclosure are
attached can be comprised of, or attached to and stabilized by, a
simple single seabed affixed pole or mono-pile (either subsurface
or protruding above the surface), (where water depths allow
(generally below 50 meters)), an offshore seabed affixed or
floating tower or platform, a seawall, or a motion-stabilized
floating frame or vessel.
[0024] When attachment is to a seabed or shoreline frame or
stabilized body, it is desirable to have either the attachment
point or the mechanical linkage adjustable for tidal depth changes
to maintain high wave energy capture efficiency and to have the
attachment points allow the float(s) to rotate in a horizontal
plane about a vertical axis to maintain their wave front parallel
orientation relative to oncoming wave fronts. Means for stabilizing
floating frames against wave heave, surge, and pitch forces and for
controlling the submerged depth of floating frames to enhance WEC
performance or to submerge the elongated floats during severe sea
conditions are described in my U.S. Pat. No. 8,614,520 and its
Continuation-In Part (CIP), application Ser. No. 14/101,325, of
which this is application is a CIP and which are incorporated
herein by reference.
[0025] The present disclosure can also utilize the wave focusing
and shoaling means described in U.S. Pat. No. 8,614,520 and it's
CIP application Ser. No. 14/101,325. Such means include a down
sloping shoaling plane affixed to either the floating frame or
other stabilizing body. Alternatively or in addition, the
protruding downward forward lip attached to the bottom of the wave
impacting forward face of the floats also captures and focuses
upward additional kinetic wave energy found deeper in the water
column.
[0026] While the subject disclosure can be pre-oriented by
attachment to fixed structures, or moored such that it's elongated
float(s) are parallel to the prevailing wave front direction, it is
advantageous for the WEC of the present disclosure to be
self-orienting, maintaining its parallel orientation to oncoming
wave fronts as they change direction from time to time. This is
especially desirable with WECs using one or more elongated floats,
like the present disclosure where the wave front facing horizontal
plane (defined hereinabove) is substantially greater than their
fore to aft horizontal depth.
[0027] The subject disclosure is advantageously self-orientating
such that its float(s) are maintained approximately parallel to
oncoming wave fronts by establishing a single up sea pivoting
attachment point above or below the still water line or SWL,
forward of the point where oncoming waves exert their lateral or
surge forces upon the one or more floats and frame. This can be
accomplished by having at least two mooring cables attached to
opposing ends of the WEC frame (outboard of the float(s) converging
at a single surface or submerged mooring buoy or point (ref. U.S.
Pat. No. 8,614,520 FIG. 13). Alternatively, rigid mounting arms on
opposing sides of the WEC frame, or shoaling planes or other
appendages thereto, can converge at a single pivot point such as a
vertical mono-pile or column (U.S. Pat. No. 8,614,520 FIG. 5
element 35) allowing horizontal rotation. Controlled underwater
vertical planes, foils, or rudders can be used, as necessary, to
offset the miss-orienting effects of any sub-surface currents or
surface winds on the WEC. It is desirable to also have any rigid
mounting arm attachments at either both ends of the WEC and/or the
pivot point, to allow the arms to pivot or slide up and down
vertically to accommodate tidal changes in the depth of the Still
Water Line (SWL).
DISTINGUISHING FEATURES OVER THE PRIOR ART
[0028] One currently popular generic WEC configuration is the
buoyant "surge flap". FIG. 1 illustrates the Oyster, a surge flap
WEC being developed by Aquamarine of Scotland. Buoyant surge flap
WECs are also being developed by Resolute Energy (US) and Langlee
of Norway (FIG. 2) among others. Surge flaps are normally deployed
on the seabed near shore in shallow water (10-15 meter depth)
because they usually pump pressurized water through seabed hoses to
shore based conventional small hydroelectric PTO systems and
because they primarily capture only the surge wave energy component
which predominates in shallow water. Near shore the seabed has
diminished/absorbed most of the heave wave energy component or
converted the remainder to surge component. Langlee, however, is a
floating deep water deployable WEC using two parallel buoyant surge
flaps hinged to a submerged frame directly driving (through a
gearbox) a generator. Buoyant surge flaps are only moderately
effective at capturing the surge wave energy component because
their single rotational axis of motion (rotation about their
stationary base hinge) makes the flaps too resistive to wave
induced lateral (surge) motion near their stationary hinged base
and too compliant (due to leverage) at the buoyant flap top.
Additionally, they are almost totally ineffective at capturing the
heave wave energy component, which is 50% of total wave energy in
"deep water" (depths exceeding 1/2 wavelength), because their
single rotational axis of motion allows almost no heave or
buoyancy-induced vertical translation of the flap above the
stationary bottom hinge.
[0029] FIGS. 11-14 disclose a means to substantially improve the
wave energy capture efficiency of prior art surge flaps. These
embodiments of the present disclosure employ "dual swing arms"
(pairs) to improve the performance of surge flaps. FIG. 11 applies
the "dual swing arms" of FIG. 10 (FIG. 11 in application Ser. No.
14/101,325) of the present disclosure to the prior art surge flaps
referenced above (either seabed mounted or offshore floating frame
mounted types). Both absorb heave and surge wave energy in several
ways. Firstly, because the flap now remains generally vertical (or
can be forward or rearward sloping depending on the relative length
and relative orientation angle of the dual swing arms 51 and 82),
the lateral wave surge forces can translate the bottom of the flap
approximately as far as the top capturing more surge wave energy.
Secondly, this dual swing arm arrangement produces greater
rotational translation of the arms about their lower arm pivot
points 52 for the same top of flap lateral translation resulting in
additional energy capture and a higher angular velocity of any gear
or direct driven generator or other type of PTO (at 15 or 77 in
FIG. 8D) driven from this rotation, for better energy generation or
PTO utilization (lower cost and/or higher efficiency).
[0030] This multi-axis rotation of dual swing arms also allows
vertical translation of the buoyant flap providing more heave
capture (and more surge capture as the flap intercepts more
vertical surge area) especially when the flap center of buoyancy,
in its neutral or SWL position, is forward of the frame dual pivot
points (per FIGS. 12-14). Utilizing the dual swing arms 51 and 82
of the present disclosure also allows a WEC using them to be
deployed deeper into the water column (or in deeper water) by
simply utilizing longer (or variable length) arms that also provide
added leverage (torque) to the PTO drive for added energy capture.
Additional water column depth and surge area can be obtained by
adding extension plates protruding from the flap bottom 5, or flap
top (not shown).
[0031] In FIG. 12, dual swing arms of the present disclosure
maintain a generic buoyant surge flap 3 in an advantageous vertical
orientation while drive bars 70 on the sides of float 3 having gear
teeth drive PTO or generator 77, located either in flap 3 (shown)
or within or attached to frame 20 (not shown). This configuration
allows concurrent and independent vertical translation of float 3
to capture the wave heave energy component while the PTO or
generator 15 captures the lateral or surge wave energy. Prior art
bottom hinged "surge flap" WECs capture little or no heave
(vertical component) wave energy.
[0032] While the buoyant flap 3 and its dual swing arms 51 and 81
can have a vertically neutral (still water line or "SWL") position
like prior art surge flaps, under the present disclosure it is
advantageous, especially in deeper water where heave and surge wave
energy components are more nearly equal, to have the neutral SWL
position angled or biased forward toward oncoming wave fronts
(advantageously around 45 degrees) to allow the flap to maximize
capture of both heave and surge. WECs using elongated floats on
swing arms hinged to stabilizing bodies or frames at points
"substantially below the water line" and oriented or biased forward
toward oncoming waves (in their neutral SWL position) are a part of
the present disclosure and were first disclosed in my U.S. Pat. No.
8,614,520 and my application Ser. No. 14/101,325.
[0033] In FIG. 13 as in FIGS. 11 and 12, the buoyant float or flap
can be biased to a forward neutral SWL position relative to hinges
52 and 80 either by using counter weights 66 on arm 67 (per FIG.
13), by adjusting the submerged depth of the floating or seabed
affixed frame or arm attachment points (52 and 80), or by applying
a forward rotation force to the arms supplied either by the PTO
system (operating in reverse) or a supplemental mechanical drive
(not shown). Wave induced float or flap rotational oscillation
about the forward tilting neutral (at SWL) swing arm angle of the
present disclosure will provide a higher combined heave and surge
wave energy capture efficiency than oscillation about either the
vertical or horizontal tilting center of oscillation of the prior
art because it provides more combined vertical and horizontal
translation and, therefore, more combined heave and surge wave
energy component capture. The elongated swing arms and dual arm or
"compound swing arms" (allowing concurrent rotation and
translation) of the present disclosure further enhances
wave-induced float translation and efficient wave energy
capture.
[0034] FIGS. 15 and 16 show alternative ways to use the present
disclosure to improve the performance of generic "surge flap" type
WECs by using either two pairs of "compound or linear motion arms"
on the ends of float 3 and laterally from frame 20 (FIG. 15
elements 70 and 72), or one pair of "compound motion arms" (FIG. 16
element 72) allowing the bottom surge flap hinge point to translate
vertically.
[0035] In FIG. 15, the lower ends of buoyant flap or float 3 are
rigidly attached to members 70 with integral or affixed gear racks
71 engaged with PTO or generator 77 drive gear 76 and idler pulleys
74 such that the buoyant flap is also permitted to independently
and concurrently translate approximately vertically in response to
the buoyant or heave forces acting upon the float. This vertical
wave-heave-force-induced translation is resisted, controlled, and
captured by secondary PTO device 77. Wave surge or lateral induced
forces on flap/float 3 are resisted, controlled and captured by
primary PTO 15 driven by lateral member 72 with gear rack 73
through pinion 13. PTOs 15 and 77 can be rotary electric,
hydraulic, linear, or magneto-restrictive electric.
[0036] FIGS. 3 and 4 depict prior art articulating raft or float
type WECs by McCabe, and Dexawave, respectively. McCabe utilizes
fore (bow) and aft floating rafts (pontoons) hinged to a center
reaction mass. McCabe's reaction mass uses seawater entrapped by at
least one submerged horizontal drag plate. The Dexawave WEC (FIG.
4) utilizes hinged rafts made of fore and aft elongated parallel
floats, but with no center reaction mass. Other prior art
articulating float WECs like the Cockerell Raft and the Pelamis use
three or more rafts without a reaction mass between them. The
Columbia Power StingRay (FIG. 5) combines the floats on arms of the
Dexawave WEC with the central drag plate reaction mass of McCabe
and substitutes a direct drive rotary PTO generator for McCabe's
hydraulic PTO. None of the prior art articulating raft or float
WECs use the connecting arms of the present disclosure with pivot
points submerged substantially below the SWL (FIGS. 8 through 21),
or substantially above the SWL (FIGS. 22-24).
[0037] Generic articulating raft type WECs including those
referenced above have several serious wave energy capture
efficiency limitations that can be overcome by the "dual swing arm"
multi-axis rotation, the "compound swing arm" multi-directional
motion, and the location of swing arm pivot points substantially
above or below the SWL of the present disclosure. Articulating
float or raft WECs depend on the wave-induced relative motion
(rotation) of their floats about their hinge joints to drive their
hydraulic or electric PTOs. Because typical wave lengths of ocean
waves or swells are long (60-180 meters) relative to their wave or
swell amplitudes (1-6 meters), the angles of relative rotation
produced about their hinge joints (located at or near the SWL) of
articulating rafts available to drive the articulating WEC PTO are
very small requiring lots of gearing or inefficient partial rotor
rotation of a direct drive generator PTO. Like the vertically
oriented bottom hinged buoyant surge flap previously described, and
because their rafts or floats are hinged at or near the water
surface, these horizontal plane articulating rafts or floats are
too resistive to vertical (heave) wave forces near their surface
hinges and too compliant at raft or float locations remote from
their hinges. Dexawave and more recently the Columbia StingRay use
floats or rafts extended from their hinge joints by lever arms to
span more wave length, but rafts or spans of 1/2 the average
expected ocean wave length would be prohibitively costly and
impractical to build.
[0038] A more serious limitation of articulating floats or rafts,
however, is the inability of the rafts or floats to significantly
translate horizontally or laterally, which is necessary to capture
the surge or lateral component of wave energy. This is so because
their hinge joint axis is located at or near the water surface. My
Rohrer U.S. Pat. No. 8,614,520 and application Ser. No. 14/101,325
(FIG. 8), of which this disclosure is a continuation, disclose and
claim one or more elongated wave front parallel floats connected to
lever arms that pivot about a stabilized point "substantially below
the water line" allowing the floats to move in a sloped or arcuate
direction "upward and rearward" during wave crests and then
"downward and forward during subsequent wave troughs" to capture a
majority of both heave and surge wave energy components. The
present disclosure further improves the concurrent capture of heave
and surge wave energy by mechanically linking one or more floats
with the "dual swing arms" and/or "compound motion swing arms" to
allow additional wave-induced concurrent and independent
horizontal, vertical, and rotational float translation with energy
capture by the same or multiple PTOs.
[0039] By allowing the fore float(s) of the present disclosure to
move or translate concurrently vertically, horizontally, and in
some embodiments, rotationally, for heave, surge, and pitch energy
capture, respectively, the present disclosure can eliminate the
need for, and cost of, the aft float of the Columbia StingRay (or
Dexawave) designs and their additional PTOs that capture a
substantially smaller portion of the oncoming wave energy not
absorbed or reflected by the fore float. The near surface hinge
joints of the Stingray front and rear floats and the short arm
length of the front float also reduces wave energy capture
effectiveness. The near and above surface portion of the center
reaction mass of the StingRay (that houses the front and rear PTO),
further masks and reflects waves forward preventing them from
reaching the rear float. The primary purpose of the rear float of
the Stingray (and the rear float shown in FIGS. 8 and 9 of the
present disclosure) is to provide enhanced pitch stabilization that
increases the rotational translation and energy capture of the fore
float. The rear float, however, may provide even more pitch
stabilization, if it is maintained at a fixed position relative to
the reaction mass or frame thereby eliminating the need and cost of
a second PTO.
[0040] If there is sufficient wave energy escaping capture by an
elongated wave front parallel fore float to justify the expense and
added WEC complexity of supplemental capture by an aft float
(oriented parallel to and rearward of the fore float), the
configurations of FIGS. 17 and 18 and FIGS. 19 and 20 of the
disclosure will capture it more efficiently than prior art
articulating raft type WECs with hinged joints at or near the water
surface. In FIGS. 17 and 18, both floats (3 and 3') use the
"compound motion swing arms" (FIG. 17), or the "dual swing arms"
(FIG. 18) of the present disclosure to rotate about separate
submerged hinge points (52 and 52') spaced horizontally apart, to
provide the downward sloped notion of both floats (upward and
rearward on wave crests and downward and forward on troughs), and
to allow concurrent multi-axis rotation or multi-directional
translation and energy absorption.
[0041] FIG. 19 describes an alternative fore and aft float
arrangement of the present disclosure with the fore float following
the more advantageous sloped path due to its hinge point being
substantially submerged below the water line and rearward of its
float as previously described. The aft float swing arm pivot point
52' could be elevated substantially above the SWL allowing sloped
movement of float 3' for improved capture efficiency. Both floats
use utilize the variable length "compound motion swing arms" of the
present disclosure to increase translation and further enhance
capture efficiency. FIG. 20 uses the same forward float and
"compound motion swing arms" as FIG. 19, but also uses the "dual
swing arms (FIG. 24) with stabilizing frame arm pivot points 52 and
80 substantially above the SWL allowing float 3' to also enjoy the
enhanced efficiency of sloped arcuate motion.
[0042] FIG. 21 shows an embodiment of the present disclosure where
one or more (two shown) elongated floats or buoyant foils rotate
about a common horizontal axis, like the Atargis WEC of FIG. 7
(that uses a horizontal axis Voith-Schneider cycloidal ship
propeller), but where the cycloidal axis of rotation 99 is on
either the fixed or variable length "compound motion swing arms" of
the present disclosure driving separate or common PTOs as
previously described, thus enhancing the wave energy capture
efficiency vs. a fixed axis horizontal Voith-Schneider or Atargis
type rotor. Unlike the FIG. 7 Atargis, the cycloidal rotor of the
present disclosure also has a rotor diameter which can be
controlled by moving variable length rotor arms 95 inward or
outward. Foil pitch is controlled by pitch control rods or cables
96. The Voith-Schneider propellers have low hydrodynamic efficiency
and are used only in low speed service ship applications where
their improved ship maneuverability is advantageous. Their
intrinsic low efficiency is due to only a portion of their
controlled pitch foils providing thrust while the others are
producing drag until they return to their starting thrust position.
When the Voith Schneider type cycloidal rotors are used in WECs,
their wave energy capture efficiency is highly dependent upon
matching rotor diameter to wave amplitude that varies wave to wave
and day to day.
[0043] Related art including Packer (U.S. Pat. No. 4,295,800),
Dullaway (U.S. Pat. No. 8,536,724), and the Wave Star of Denmark,
all describe WECs utilizing round or elongated floats with arcuate
motion dictated by swing arms of constant length pivoting about a
point or horizontal axis substantially above the still or mean
water line rather than below the SWL per previously described
embodiments of the present disclosure, or at the SWL per Columbia,
McCabe, Cockerell and others. Their floats are lifted out of the
water for survival during severe sea conditions rather than
submerged per previously described embodiments of the present
disclosure.
[0044] Utilization of the "compound" variable length arms or dual
arms of the present disclosure can substantially increase wave
energy capture efficiency of floats on swing arms pivoting about a
point substantially above the SWL by allowing increased concurrent
vertical and lateral float displacement during each wave cycle as
depicted in FIGS. 22-24. In FIG. 22, a float located below and
rearward of its swing arm pivot point 52 (like Dullaway) swings
upward and rearward in response to oncoming wave crests. By
utilizing the variable length "compound swing arm" of the present
disclosure driving a common 77 or supplemental PTO (not shown),
additional arm rotation and horizontal and vertical float
translation occurs resulting in additional energy capture.
[0045] In FIG. 23, a float below and forward of its connecting
lever arm pivot point 52 (like the Wave Star) likewise obtains
additional lever arm rotation and float translation and energy
capture utilizing one or more (or pairs of variable length
"compound swing arms" of the present disclosure. Without the
"compound swing arms" of the present disclosure, floats extending
on swing arms toward oncoming wave fronts from seawalls or piers
have virtually no lateral translation from oncoming wave front
lateral surge forces and hence minimal surge wave energy capture
ability.
[0046] In FIG. 24, a float is rearward of one or both of the swing
arm pivot points of its two, approximately parallel, "dual swing
arms". This maintains or controls the float's orientation
(preventing float rotation) during its travel allowing the float
with any appendages to maintain a deeper penetration into the water
column and optimal front face wave impact angle for more surge and
heave energy capture during its wave induced translations. The
embodiments of the present disclosure shown in FIGS. 22-24 can be
applied to elongated or other floats that are submerged under,
lifted above, or maintained in the water during severe wave
conditions.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] FIG. 1 is a view in elevation of a related art WEC by
Aquamarine Oyster.
[0048] FIG. 2 is a submerged bottom isometric view of a related art
WEC by Langlee Robusto.
[0049] FIG. 3 is a sectional view of a related art WEC by McCabe
Wave Pump.
[0050] FIG. 4 is a top isometric view of a related art WEC by
Dexawave.
[0051] FIG. 5 is an isometric view of a related art WEC by Columbia
StingRAY.
[0052] FIG. 6 is a submerged bottom isometric view of a related art
WEC by Atargis.
[0053] FIG. 7 is a submerged bottom isometric view of the related
art WEC shown in FIG. 6 with attached sensors and actuation
control.
[0054] FIG. 8 is a view in elevation of a WEC with a subsurface
hinged active fore float and a surface hinged static or active rear
float according to one embodiment of the disclosure.
[0055] FIG. 9 is a plan view of the floats shown in FIG. 7.
[0056] FIG. 10 is an elevational view of a WEC with parallel "dual
swing arms" and optional shoal plane according to another
embodiment of the disclosure.
[0057] FIG. 11 is a view in elevation and in partial phantom of a
surge flap WEC with "dual swing arms" according to a further
embodiment of the disclosure.
[0058] FIG. 12 is a view in elevation and in partial phantom of the
surge flap WEC shown in FIG. 11 with a supplemental PTO or
generator according to yet another embodiment of the
disclosure.
[0059] FIG. 13 is a view in elevation of a surge flap WEC shown in
FIG. 11 with a counterweight arm according to yet another
embodiment of the disclosure.
[0060] FIG. 14 is a view in elevation and partial phantom of the
surge flap WEC shown in FIG. 11 with a supplemental or secondary
PTO according to another embodiment of the disclosure.
[0061] FIG. 15 is a view in elevation of a surge flap WEC with
compound x-y axis drives according to a yet further embodiment of
the disclosure.
[0062] FIG. 16 is a view in elevation and in partial phantom of a
surge flap WEC with a compound x axis drive on a bottom hinged flap
gate according to a still further embodiment of the disclosure.
[0063] FIG. 17 is a view in elevation of a WEC with dual floats
each with a subsurface pivot point "compound motion swing arms"
according to yet another embodiment of the disclosure.
[0064] FIG. 18 is a view in elevation of a WEC with dual floats
with subsurface pivot point "dual swing arms" according to still
another embodiment of the disclosure.
[0065] FIG. 19 is a view in elevation of a WEC with a fore float on
subsurface pivot point "compound motion swing arms" with compound
drives and an aft float with "compound motion swing arm" with PTO
drives on or near the water surface (SWL) pivot point according to
a further embodiment of the disclosure.
[0066] FIG. 20 is a view in elevation of a WEC with a fore float on
subsurface pivot point "compound motion swing arms" with compound
drives and an aft float with "compound motion swing arm" pivot
point with PTO drives substantially above the water surface (SWL)
according to a still further embodiment of the disclosure.
[0067] FIG. 21 is a view in elevation of a WEC with a buoyant wave
driven cycloidal rotor on subsurface hinged "compound motion swing
arm" according to a yet further embodiment of the disclosure.
[0068] FIG. 22 is a view in elevation of a WEC with a float
trailing above a surface pivot point "compound motion swing arms"
according to another embodiment of the disclosure.
[0069] FIG. 23 is a view in elevation of a WEC with a float leading
above surface hinged leading swing "compound motion swing arms"
according to yet another embodiment of the disclosure.
[0070] FIG. 24 is a view in elevation of a WEC with float trailing
parallel "dual swing arms" with above surface pivot points
according to still another embodiment of the disclosure.
[0071] FIG. 25 is a view in elevation of a WEC with fore and aft
floats each surface hinged to a frame/reaction mass with "dual
swing arms" with pivot points located approximately at the water
surface (SWL) according to a further embodiment of the
disclosure.
[0072] It should be understood that similar reference characters
denote corresponding features consistently throughout the attached
drawings and that similar reference characters with or without
prime designations denote corresponding features in different
embodiments of the disclosure.
DETAILED DESCRIPTION OF THE DISCLOSURE
[0073] The features and limitations of the Prior Art WECs of FIG. 1
through FIG. 4, inclusively, are previously described in the
previous DISTINGUISHING FEATURES OVER THE PRIOR ART section and in
my U.S. Pat. No. 8,614,520 and U.S. application Ser. No. 14/101,325
of which this is a Continuation. The discussions of those related
references are referenced here to provide perspective to the
following detailed description.
[0074] FIG. 6 is an embodiment of the present disclosure similar to
FIG. 7 in application Ser. No. 14/101,325 wherein one or more (two
shown) elongated buoyant float(s) or barrier(s), 3 and 60, having a
wave front facing and impacting forward face which face may be
concave (shown as 1 on the fore float 3), flat (shown as 1 on the
aft float 60), or convex (not shown) and being rigid (shown),
hinged (not shown) or flexible or compliant (not shown). The
float(s) bottom 2 can be flat and angled approximately parallel to
the float's direction or arc of motion (as in bottom 2 shown in
FIGS. 10, 13, 17-20, and others) or arcuate 2 as shown herein to
reduce drag and minimize the formation of an energy consuming "back
wave" as the float is driven rearward and upward by the lateral
surge forces and vertical heave or buoyant forces of oncoming waves
6 impacting face 1. Buoyant floats 3 and 60 can be solid or foam
filled (like 60) or hollow (like 3). The float(s) may have an
attached protruding lower lip or "shoaling plane" 5 that allows the
float to penetrate deeper into the water column capturing
additional surge (lateral/kinetic) wave energy. The float(s) and
forward face 1 are advantageously pre-oriented toward prevailing
wave fronts or self-orienting parallel to oncoming wave fronts
6.
[0075] Forward float 3 is rotatably connected by two swing arms 51
on opposite sides of the float to the two vertical spar sections of
motion stabilized frame 20 at connection pivot points 52 located
substantially below the normal operating Still Water Line or "SWL"
18. Float 3 advantageously, either individually or collectively
with adjacent floats, is elongated having a wave-facing
front-facing width substantially exceeding its fore to aft depth
allowing the float to intercept and capture a maximum amount of
energy containing wave front per unit of float volume, weight, and,
therefore, cost. Oncoming waves 6 rotate float 3 both rearward (by
impacting its forward face 1) and upward (due to the upward buoyant
forces of wave 6 on the float). The rearward rotation of float 3
and arm 51 is resisted by bull gear 12 driving pinion gear 13 on
primary generator or other PTO 15 (with or without a gear box).
Alternatively, a generator 15 can be directly driven (with or
without a gear box) by swing arm 51 at pivot point 52. One or more
optional pivoting louvers 45 are pivotably mounted on 51 and span
the float driven swing or lever arms 51. Their eccentric hinges 46
and return springs (not shown) allow them to rotate flat (parallel
to wins 51 when oncoming wave fronts apply surge wave pressure
against them and then rotate open (dotted positions) when arms 51
are returning during subsequent wave troughs.
[0076] Rearward float 60 is mechanically linked to stabilize frame
vertical spars 20 by arm 58 and optional arm extension 59 that can
pivot about point 62 located at or near the SWL (as shown in FIG.
8). Total arm length (59 plus 58) can, optionally, be adjustable by
allowing 59 to slide within or along 58. The primary function of
aft float 60 is to provide pitch stability to frame 20 as both
lateral (surge) and vertical (heave) wave forces against float 3
are applied to frame 20 through the resistive torque of generator
or other PTO 20 forcing it to rotate/pitch rearward
(counterclockwise). If float 60 is used for pitch stability only,
arms 58 are locked into a horizontal position approximately normal
to vertical frame spars 20 during WEC operation. Alternatively, arm
58 can be free to rotate about hinge points 62 driving generator or
other PTO 15 or a secondary generator or PTO (not shown). Float 60
will capture substantially less wave energy than float 3 because
(1) float 60 is effectively masked by float 3, and (2) its hinge
point 62 is at or near the SWL that does not allow float 60 to
translate in the more effective upward and rearward direction with
oncoming wave crests. Placing hinge point 62 "substantially above
the SWL" 18 (such as at or near frame cross beam 61) while not
shown in FIG. 8, would provide a more advantageous embodiment
allowing float 60 to move both upward and rearward during oncoming
wave crests to capture more surge (lateral) wave energy component
(see also FIG. 24).
[0077] With almost no lateral movement or translation, float 60
will capture very little surge wave energy component (which is 50%
of total wave energy in deep water). If float 60 swing arms 58 are
unlocked and it is used for supplemental wave energy capture, it
will also provide less pitch stability to frame 20 that will reduce
the rotation and hence, wave energy capture by primary float 3
(partially or completely offsetting float 60's supplemental
generation). Arms 58 can be unlocked and allowed to swing to a
vertical position when the stabilizing frame is submerged during
severe sea conditions allowing float 60 to provide sufficient
residual buoyancy to prevent float 60 from sinking below SWL 18
when frame ballast tank 24 and primary float 3 are flooded for
submergence during severe sea conditions. Primary float 3 arms 61
are so arranged (i. e. inboard) relative to arms 58 such that these
arms and their floats do not interfere with each other as they
swing through their travel arcs.
[0078] Stabilizing frame 20 with its lower seawater adjustable
ballast section 24 and fixed high density ballast 21 either alone,
or in combination with, floats 3 and 60 have net positive buoyancy.
During severe sea conditions, primary forward float 3 can be fully
submerged below oncoming wave troughs for protection either by
controllably flooding lower frame section 24 with seawater 23
through ports 30 by releasing compressed air in the upper portion
of frame section 24, or forcing float 3 into submergence either
using PTO or generator 15 in reverse or using a supplemental drive
rotating arms 51 downward. A hollow interior cavity 4 of float 3
can be controllably partially filled (to level 7) with seawater
through controlled apertures 57 to adjust float mass for optimized
wave energy capture efficiency for a given sea state or completely
filled to reduce or eliminate float 3 buoyancy to facilitate its
total submergence. The buoyancy of float 3 can be re-established by
raising float 3 with PTO or generator 15 or an alternative drive
(not shown) allowing seawater to exit through controllable or
one-way drains 8. The frame's adjustable buoyancy level can also be
used to establish the optimal rotational arc of travel of arms 51
for maximum energy capture efficiency for a given operational sea
state.
[0079] Drag plate extensions 33 provide heave stability to the
frame and may be hinged at their connection to horizontal drag
plates 32 for reduced drag when recovering downward during wave
troughs. The drag plates and their extensions may extend between
the twin frame vertical spar members 20 and 24. The frame may have
additional cross members 61 to maintain rigidity between the
vertical frame spar members. Mooring cables 31 that converge at a
single up-sea pivoting point (mooring buoy, vertical piling or the
like, not shown) are attached to each of the two stabilizing frame
vertical spars either near the bottom (as shown) or at a higher
elevation to improve frame pitch stability as necessary.
[0080] FIG. 9 is a plan view of an embodiment of the present
disclosure very similar to FIG. 8. It also shows a torsionally
rigid tube 68 with mid span support bearing 69 that keep port and
starboard side swing arms 51 from placing high stresses on their
connection with float 3 when waves apply uneven forces upon the
port and starboard side of float 3. FIG. 9 also shows an
arrangement whereby neither float 3 nor float 60 and their
respective swing arm pairs 51 and 58 can interfere or contact each
other as they rotate about their pivot or hinge points 52 and 62,
respectively.
[0081] FIG. 10 is a full elevation view similar to FIG. 8 (and FIG.
11 of U.S. application Ser. No. 14/101,325 included by reference)
describing the "dual swing arms" of the present disclosure with
dual approximately parallel swing arms 51 and 82, respectively,
swinging about substantially submerged pivot or hinge points 52 and
80 and also pivotably connected to primary float 3 at hinge points
63 and 81, respectively. Swing arms 52 either drive generator 15 at
pivot point 52 or drive a generator through bull gear 12 and pinion
gear 13. The use of the "dual swing arm" float-to-frame mechanical
linkages of the present disclosure substantially enhances the
performance of either generic buoyant bottom-hinged vertical "surge
flap" type WECs or generic near-surface-hinged horizontal floating
"articulating raft" type WECs by concurrently increasing both the
vertical and horizontal translation or movement of the entirety of
such buoyant flaps, floats, or rafts (especially the areas near
their stationary hinge points). The "dual swing arms" also provide
control of the orientation of vertical wave impacting forward face
1 of float 3 throughout the entire wave cycle and float stroke
maximizing the water column penetrating vertical depth of face 1
and any attached face extension plates 5. Further description and
advantages of the "dual swing arms" of the present disclosure over
generic "surge flap" and "articulating raft" type WECs are provided
in the preceding DISTINGUISHING FEATURES OVER THE PRIOR ART
section.
[0082] FIG. 10 also describes the use of a shoaling plane 54 with
optional vertical converging side shields 44 (similar to that shown
in my U.S. Pat. No. 8,614,520 at FIG. 5, elements 40 and 41) that
further penetrate deeper vertically into the water column and focus
oncoming waves toward float 3 for additional surge wave energy
capture. Plane 54 can be attached to the stabilized frame by shoal
plane mounting members 42 with pivoting connection points 78 such
that plane 54 rotates downward when float 3 reaches its extreme
downward position and would otherwise contact plane 54. It
subsequently returns to its normal position using return springs at
one or more pivot points 78 (not shown). Alternatively, frame 42
can be rigid using added members 79.
[0083] FIG. 10 shows the arc of travel of "dual swing arms" 51 and
82 (solid and dotted lines) providing a favorable down sloped
direction of movement of float 3 that moves both upward and
rearward during wave crests and returns forward and downward during
ensuing wave troughs thus providing both lateral (horizontal) and
vertical float movement or translation that, in turn, provides
enhanced heave and surge wave energy capture efficiency over
related art vertically oriented (in neutral SWL position) "surge
flaps" or horizontally oriented "articulating rafts" that capture
primarily surge or heave wave energy, respectively, but not
both.
[0084] FIG. 11 shows a sectional elevational view of an embodiment
of the present disclosure where "dual swing arms" enhance the
movement or translation and, therefore, the wave energy capture
efficiency of vertically oriented buoyant "surge flaps". This
embodiment illustrates that the "dual swing arms" of the present
disclosure (arms 51 and 82) need not be parallel to one another or
of equal length, and the swing arm hinge or pivot points to the
stabilizing frame or other stabilizing body (52 and 80), or to the
float 3 (pivoting attachment points 63 and 81), need not be in
horizontal or vertical alignment. As shown in FIG. 11, both the
frame and float attachment points are sloped and the arms are of
unequal length. This configuration allows the float forward face 1
to rotate slightly clockwise (with wave fronts approaching from the
right) while the "dual swing arms" are rotating counterclockwise
such that the float is translating both laterally and vertically
for added surge and heave energy capture. Either arm can drive the
generator or PTO 15 (here arm 51 is doing so at pivot point 52) and
the neutral orientation of the "dual swing arms" (at the still
water line) can be forward of their lower pivot points 52 and 80 so
as to add heave and surge capture efficiency of the down sloped
direction of motion previously described (in FIG. 10 and
elsewhere).
[0085] In FIG. 12, another vertically oriented buoyant "surge flap"
type float embodiment is shown that is an improvement over the
prior art "surge flaps" in that it combines "dual swing arms" (as
previously described) pivotably attached to flap attached
horizontal cross members 72 on the sides of the buoyant flap. The
buoyant flap is provided with additional vertical translation
capability by float 3 rigidly attached drive arm 70 with rack gears
71 that move vertically between idler rolls 74 and pinion gear 76
driving a secondary PTO or generator 77 (similar to FIG. 15).
Alternatively, vertical drive arm 70 engaging PTO or generator 77
can be mounted on stabilized or stationary frame member 20 (not
shown). Some generic surge flaps that are usually deployed with
their frames attached to the seabed in shallow water near shore,
use their PTOs to submerge their buoyant flaps during severe sea
conditions by rotating them away from oncoming waves to a near
horizontal position. This can also be done with the improved dual
swing array embodiments of the present disclosure by pivotably
attaching the forward swing arm 82 to frame attached horizontal
cross member 89 that itself can be released from the frame 20 and
controllably rotated about point 52 allowing the entire flap
(float) 3 to lay horizontal until severe sea conditions
moderate.
[0086] FIG. 13 shows a partial elevation view of another embodiment
of the present disclosure (similar to FIG. 11 of my application
Ser. No. 14/101,325) using the "dual swing arms" to improve the
combined heave and surge wave energy capture efficiency of related
art "surge flap" type WECs or other WECs with hinged or pivoting
surface floats by maintaining float wave impacting face 1 vertical
while biasing the swing arms forward either by adjusting the
submerged depth of the arm to frame pivot or hinge points (52 and
80) relative to the SWL 18, and/or by adding forward hanging
counterweight 66 attached to, and forward of, forward swing arm 82
from counterweight arm 67 attached to 82.
[0087] FIG. 14 shows a partial elevation view of another embodiment
of the present disclosure using dual swing arms 51 and 70 pivotably
attached to float 3 at points 63 and 81, respectively. Arm 51 is of
fixed length as in FIGS. 11-13, and pivots about point 52 to drive
PTO or generator 15 through bull gear 12 and pinion 13. Arm 70,
however, pivoting about 80 is of variable length having gear teeth
71 driving secondary PTO or generator 77, or also driving primary
PTO 15 (not shown). This variable length dual swing arm allows
float 3 to also rotate about its bottom pivot point 63 for
additional energy capture. Variable length swing arms of the
present disclosure are also referred to herein as "compound swing
arms".
[0088] In advantageous embodiments of the present disclosure, it is
desirable to have the one or more surface floats pivoting upward
and rearward during oncoming wave crests and forward and downward
on ensuing wave troughs. This requires the single or dual, simple
or compound, swing arms of the present disclosure to lie at a
forward biased angle if swinging about one or more substantially
submerged pivot points or at a rearward biased angle if pivoting
about one or more substantially elevated pivot points. This differs
from the vertical orientation of related art "surge flaps" or the
horizontal orientation of related art "articulating rafts" or
floats relative to the SWL. A neutral bias angle of 45 degrees
forward of vertical upward is ideal for swing arms hinged aft of
their respective floats and "substantially below the SWL" (45
degrees aft of vertical downward is therefore ideal for floats
trailing hinge point(s) substantially above the SWL).
"Substantially above" or "substantially below" as used herein refer
to a hinge point location above or below the SWL greater than 1/3
of the radial length or distance from the hinge point to the
extremity of the float or flap. This can be accomplished in any of
the embodiments of the present disclosure whether using single or
dual, simple or compound, swing arms by (1) raising or lowering the
hinge points below (or above) the SWL (either by changing the
elevation or submerged depth of the "stabilizing frame or body" to
which the hinge points are attached, (2) changing the elevation of
the hinge points relative to the "stabilizing frame or body",
and/or (3) changing the radial length from the hinge point(s) to
the center of buoyancy of the floats or flaps such as by using
variable or adjustable length, or compound swing arms.
[0089] FIG. 15 shows a partial elevation of an embodiment of the
present disclosure (also shown in FIG. 10 of Ser. No. 14/101,325)
wherein two "compound motion arms" of the present disclosure, one
shown vertical 70 and the other shown horizontal 72 allow a
vertically elongated "surge flap" type float 3 to concurrently move
(translate) concurrently both vertically (for wave heave energy
capture) and laterally (for surge energy capture) with both
translations driving either a single PTO or generator (or hydraulic
pump) 77 with horizontal arm 72 rigidly attached to frame member
20. Alternatively, arm 72 can travel horizontally between idlers 74
and pinion gear 13 on frame member 20 driving separate PTO or
generator 15.
[0090] FIG. 16 shows a partial elevation of an similar embodiment
of the present disclosure wherein a generic bottom hinged "surge
flap" type WEC with a vertically elongated float 3 on arms 51 is
improved by adding a lateral "compound motion arm" or track 72 that
allows the bottom hinge 52 to translate laterally on carriage 75
traveling on track 72 with idler rolls 74. Gear rack 73 on top of
track 72 engages pinion gear 76 driving secondary generator 77 or
other PTO while flap 3 is concurrently rotating about the hinge
point 52 driving primary PIO 15. Track 72 is rigidly mounted on
lateral frame member 20 firmly affixed to the seabed 28 or other
stabilized body (not shown). Dotted flap position 3'' shows the
flap lying horizontal for protection from severe sea conditions.
Additional performance improvements over generic "surge flaps" can
be obtained by establishing a forward biased neutral (SWL) position
for float/flap per 3', providing a variable length mechanism within
arm 51 or within its attachment to float/flap 3 (such as shown in
FIG. 8 variable length arms 58 and 59) to compensate for tidal
changes in SWL 18, or using the "compound motion arm" of FIGS. 15,
17, or 19 and 20.
[0091] While many of the previous and following figures and
descriptions of embodiments of the present disclosure describe the
use of geared or direct drive rotary electric generators (currently
gaining popularity in WEC devices) other PTO types can be readily
substituted without materially parting from the spirit and scope of
the disclosure including, but not limited to, PTOs using low or
high pressure hydraulic piston/cylinders (using water or hydraulic
fluid, respectively) to power water turbine or rotary hydraulic
motor driven electric generators.
[0092] Likewise figures and descriptions of the "compound motion
arms" of the present disclosure are depicted as using rack and
pinion linear drives. Other linear type PTO drives can readily be
substituted including direct drive linear electric generators,
helix or ball screw type linear to rotary drives, and capstan
cable, gear, cog, or other belt drives, and chain drives without
departing from the present disclosure. It should also be noted that
any of the embodiments of the present disclosure can utilize
protruding lower lip 5 shoal plane 64 of FIG. 10 to penetrate
deeper into the waver column for additional wave energy capture.
Any of the embodiment s of the present disclosure can likewise
utilize partial or full submergence of the one or more floats as
described in my U.S. Pat. No. 8,614,520, or my application Ser. No.
14/101,325, or per FIG. 10 of the current disclosure for float and
WEC protection during severe sea conditions, or to optimize WEC
wave energy capture in any specific sea condition.
[0093] FIG. 17 provides a partial elevation view of an embodiment
of the present disclosure utilizing one (not shown) or two floats
or flaps, 3 and 3' (shown) mechanically linked using compound swing
arms 51 to horizontally oriented partial frame or other stabilizing
body section 20. In both FIGS. 17 and 18, compound swing arms 51
oriented or neutrally biased (at SWL level 18) forward (rather than
vertical like generic surge flaps) produce the more desirable
sloped arcuate motion of floats 3 as previously described. When
"surge flaps" are deployed near shore in shallow water (under 20
meters), where most of the available wave energy is surge not
heave, employing the sloped motion of several embodiments of the
present disclosure to float or flaps 3 rather than the forward and
rearward rotation around a vertical neutral (SWL) position used by
generic "surge flaps", may provide a relatively small performance
gain. When "surge flaps" are used in "deep water" (depths greater
than 1/2 average wave length), however, like the Langlee WEC, major
gains can be realized from the forward bias produced sloped motion
of the present disclosure.
[0094] "Compound swing arms" 51 are configured to allow concurrent
lateral movement along their length to drive secondary generator 77
with pinion gears 76 that are, in turn, driven by rack gears 73 on
arms 51 and simultaneously allow arcuate rotation of arms 51 about
pivot points 52 to drive primary generators 15 (not visible, but
concentric and inboard or outboard of generator 77). During initial
impact of float 3 front face 1 with oncoming wave 6, float 3 exerts
a downward (compressive) force on arms 51 causing attached gear
rack 73 to rotate generator 77 through pinion gear 76.
Concurrently, both wave lateral surge forces and vertical heave
(buoyant) forces on float or flap 3 cause a counter-clockwise
rotation of arms 51 driving primary generator 15. During ensuing
wave troughs, the translation and rotation of arms 51 are reversed
and drive generators 76 and 15 in the opposite direction (unless
reversing gears are used with or without ratcheted flywheels).
[0095] FIG. 18 provides a partial elevation of an embodiment of the
present disclosure similar in function to FIG. 10, but using two
floats or flaps 3 rather than one mounted on a lateral frame or
stabilizing body member 20 (shown in partial view). If there
remains sufficient uncaptured wave energy passing through the
forward float or flap 3 to justify use of a second float or flap
3', then using the two down sloped motion floats shown in FIG. 18
will provide superior capture efficiency over the two float
configuration of related art FIG. 5 (Columbia StingRAY) because
both floats utilize the advantages (as previously described) of
both the down sloped capture motion and the dual swing arms of the
present disclosure.
[0096] FIG. 19 provides a partial elevation of another two float or
flap (3 and 3') embodiment of the present disclosure configured
like FIG. 8 (with forward float 3 hinged about point 62 to partial
frame section 20 substantially below the SWL and rearward float 3'
hinge point 52' at or near the SWL). The embodiment shown in FIG.
19, however, utilizes the "compound motion arms" of FIG. 17 that
allow concurrent rotation and translation for additional energy
capture.
[0097] FIG. 20 provides a partial elevation of another two float or
flap (3 and 3') embodiment of the present disclosure. The front
float 3 utilizes compound motion arms as in FIG. 19 while the rear
float 3' uses the dual swing arms (51 and 82) as previously
described, but with the dual arm pivot points (52 and 80)
substantially above the SWL and forward of float 3' resulting in
the desirable sloped motion of float 3' providing enhanced heave
and surge wave energy capture by PTO or generator 15 through bull
gear 12 and pinion gear 13.
[0098] FIG. 21 provides a full elevation view of an embodiment of
the present disclosure that combines the "compound motion arm" 51
(per FIGS. 17 or 19 and 20) with a twin rotor 94 horizontal axis
cycloidal Voith-Schneider type propeller or rotor assembly driving
generator or PTO 102 with wave-induced forces on rotor blades 94,
the assembly having net positive buoyancy and thus reacting like a
float or flap. The twin rotors have pitch control rods or cables 96
that are independently controlled to maximize the net wave induced
torque on the rotor about point 99. The rotor blades 94 are
supported by rotor arms 95 that are optionally of adjustable length
for adjustment to varying average wave amplitudes, using gear racks
97 driven by pinion 98. As in FIGS. 17, 19 and 20, the one or more
compound arms 51 drives generator or PTO 77 gear rack 73 and mating
pinion 76 via its translation and concurrently drives generator or
PTO 15 via its rotation about pivot point 52.
[0099] The "Compound motion arm" drive assembly is mounted on
lateral truss 103 that provides a stabilizing base. Truss 103 is
attached to seabed 28 affixed pole or piling 35 through slide and
pivoting joint 36 such that it is free to both move slowly
vertically to adjust for tidal changes in the SWL 18 and to rotate
in a horizontal plane to keep the rotor axis parallel to oncoming
wave fronts 6. The net buoyancy of all WEC components affixed to
pole 36 is net positive. During severe sea conditions, arm 51 can
he rotated downward (clockwise) and/or joint 36 can be pulled
downward toward the seabed by a tension cable or other supplemental
drive (not shown) for survival protection. The rotor (or any of the
WECs with elongated floats or flaps of previously described
embodiments of the present disclosure) will self-orient itself
parallel to oncoming wave fronts as long as the wave induced
lateral (surge) forces acting against such elongated rotors, floats
or flaps are down-sea of the pole, piling, tower, mooring buoy or
other pivoting attachment point.
[0100] FIGS. 22-24 illustrate how the "compound motion arms" or
"dual swing arms" of the present disclosure can also be applied to
WECs where the one or more swing arm pivot points are above the SWL
rather than at or advantageously below the SWL per previously
described embodiments. In FIG. 22, the "compound motion arms"
embodiment of the present disclosure, as described in FIGS. 17 and
19-21, are mounted on a motion stabilized frame or body member 20
such that buoyant float or flap 3 is trailing arm pivot points 52
located above the SWL thereby allowing the more effective
down-sloping motion of float 3 that increases the capture of both
heave and surge wave energy components as previously described. The
less desirable configuration with float 3 preceding the "compound
motion arm" pivot point 52 as shown on FIG. 23 is also an
embodiment of the present disclosure. In this embodiment, the
compound drive or PTO mechanism including primary generator 15 and
secondary generator 77 (shown of equal diameter and inboard or
outboard of each other) are mounted on a seawall, breakwater, or
other stabilized body.
[0101] In FIG. 24, the "dual swing arms" embodiment, as previously
described in FIGS. 10-13 and 18 one or both dual arm pivot points
80 and 52 on stabilized frame or body member 20 are mounted above
the SWL and above float or flap pivot points 81 and 63 such that
float 3 moves in the more desirable downward-sloped direction
moving upward and rearward during oncoming wave crests 6 and
returning downward and forward on ensuing wave troughs. The less
desirable configuration with float 3 preceding pivot points 80 and
53 is not shown, but is also an embodiment of the present
disclosure.
[0102] FIG. 25 depicts an elevation view of the present disclosure
where fore and aft floats (3 and 3') are mechanically linked by
"dual swing arms" (51 and 82 fore and 51' and 82' aft) to
stabilized frame 20 "at or near the SWL" at hinge points 52 and 80
fore and 52' and 80' aft. The "dual swing arms" are otherwise as
described in FIGS. 10, 11, 13, 18 and 24. FIG. 25 (unlike FIGS. 8
and 10) also shows a truss 100 located between the dual (port and
starboard) vertical spar frame upper members 20 and lower spar
frame member 24 with integral ballast tank as well as port and
starboard mooring cables 31 that converge at an up-sea mooring that
functions as another pivot point (not shown).
[0103] Generic "articulating raft" type WECs (related art McCabe,
Dexawave, and Stingray shown in FIGS. 3-5 respectively, use raft or
float hinge points "at or near the SWL". This generic configuration
can be substantially improved by using the "dual swing arms" of
FIG. 25 of the present disclosure.
[0104] Embodiments of the present disclosure using both fore and
aft floats, if needed, and placing the fore float hinge points to
the fixed or stabilized frame or body "substantially below the SWL"
(like those shown in FIGS. 10, 11, 13 and 18) and the aft hinge
points to the stabilized frame or body "substantially above the
SWL" (as shown in FIG. 23), while not specifically illustrated
herein, are advantageous over the FIG. 14 configuration (because
they produce the advantageous down sloped swing path for both
floats) and are a part of the present disclosure. Embodiments using
any combination of "dual swing arms" and "compound swing arms"
connecting one or more floats with arms hinged below, near, or
above the SWL are, likewise, a part of this disclosure. Embodiments
utilizing single (simple) swing arms linked to fore and aft
elongated floats with the fore float to frame linkage below the SWL
and the aft float linkage above the SWL are likewise embodiments of
the present disclosure as are dual float single swing arm
configurations where both fore and aft frame hinge points are both
below or both above the SWL.
[0105] The elongated wave front parallel floats of the present
disclosure are fully submergible during severe sea states by: 1)
PTO or auxiliary drive forced float submergence, 2) increasing the
submerged depth of the stabilizing frame or body connecting arm
hinge points, and/or 3) reducing the combined buoyancy of the
stabilizing frame and at least one float by allowing seawater to
enter cavities in either or both. These float submergence methods
and those described in my application Ser. No. 14/101,325 can
likewise be applied to all embodiments of the present disclosure
including the use of variable and controlled buoyancy floats and
frames either to facilitate their partial or total submergence (and
re-emergence), or to optimize their mass for improved
performance.
[0106] Most embodiments of the present disclosure described in the
specification and depicted in the drawings utilize matching pairs
of swing arms or axial drives on either side of elongated floats.
Because wave-induced forces on either end of such elongated floats
will seldom be equal, horizontal "torque tubes" (68 in FIG. 9) or
comparable connections can be utilized at any or all pivot points
in any embodiments to prevent such unequal loads from "racking" the
elongated floats and their swing or connecting arms.
[0107] The present disclosure is not limited to the specific
configurations and descriptions presented herein but also applies
to other applications and combinations of the principles
disclosed.
* * * * *